Printing mechanism for adding machines



May 5. 1942. T. o. MEHAN 2,281,851

PRINTING MECHANISM FOR ADDING MACHINES 3 Sheets-Sheet 1 ,May 5, 1942.

T. o.l MEHAN PRINTING MECHANISM FOR ADDING MACHINES :s sheets-sheet 2 lll May 5, 1942.

T. o. MEI-IAN 2,281,851

.PRIENTING MECHANISM FOR ADDING MACHINES Filed Feb. 1, 1937 3 Sheets-Sheet I5 erga-1,5 gmk/5f.

Patented May 5, 1942 UNITED PRINTING YMECHANISM FOR ADDING YMACHINES Thomas O. Mehan, Chicago, Ill.,v assignor to Y Victor Adding Machine Co., Chicago, Ill., a corporation of Illinois Application Februaryv 1, 1937; SerialN'o. 123,320

.(Cl. lOl-96) Claims.

My invention relates generallyeto Aadding and listing machines, and more particularly toV improvements in the printing mechanism used in such machines.

It is an object oi my invention toprovide an an improved visible printing mechanism for adding machines, using rotatable type carrying wheels as the impression members.

A further object isl toprovide an improved paper feeding mechanism for adding machines.

A further object is to provide an improved full stroke mechanism for adding machines and the like.

Another object is to provide an improved printing mechanism for adding machines whichl is substantially noiseless in operation.

A further object is `to provide a printing mechanism for adding machines and thelike in which the type are moved seriatim against the paper upon which the impression is tobe made, thereby decreasing the noise of operation.

A further object is to provide an improved printing mechanism for adding machines, in which the use of hammers forl striking the type has been obviated.

Other objects will appear from the following i description, reference being had to the accompanying drawings, in which:

Fig. l is a central longitudinal sectional view oi the machine;

Fig. 2 is a sectional view taken on the line 2-2 of Fig. l;

Fig. 3 is a side elevational view of one of the type arm restraining latches;

Fig. 4 is a fragmentary sectional View taken on the line 1& 4 of Fig. 1;

Fig. 5 is a fragmentary sectional view taken on the broken sectional line 5-5 of Fig. l;

Fig. G is a fragmentary horizontal sectional View taken on the line 6--6 of Fig. 1; and

Fig. '7 is a longitudinal sectional view of. the rear portion of the machine showing particularly the full stroke mechanism and the platen actuating means.

My present invention is illustrated as embodied in an adding and listing machine of the i ten key, traveling carriage type, although many features of the invention may be utilized in mashines of other types. The adding machine is shown as comprising a base I0 to which a right side frame plate I2 and. a left side frameplate-M aresuitaicfly` secured. The major portion of the mechanism'is `enclosed in a casing I6 which is preferablyY anintegral'die casting. lThe adding machine features are not completely illustrated, since they-may beof' any well-known construction andv `include the usual control keys and mechanisms. Ihave, however, shown the most important Velem-ents of the adding machine as comprising a set` of numeral keys yIt having oiset and aligned key stems mounted for sliding mcvementin suitable slots'formed in a key plate 22. 1 Each of the key stems is provided with a suitable return spring not shown in the drawings. The-ends of the-key stems 20 are cooperable with stop pinsv 24' mounted for longitudinal movement inra' pincarriage 25 which is suitably mounted for slida'ble'movement upon rods 28 and 35. A zero stop plate 32 is pivotally connected tothe carriage and has a downwardly projecting iiange 3'4 to serve as avzero stop for such of the actuating racks as are not to be moved from their normal positions, in the manner well-known in the art, and disclosed in my prior Patent No. 1,899,444, dated February 28, 1933.

It will be understood that. upon successive depression ofselected numeral keys I8, stop pins 24 corresponding to the keys depressed, will likewise be. depressed and resliently or frictionaily held irl-depressed position, and` that after each successive operation of one ofthe keys I8, the carriage 26 will be moved to the left (looking at the front ofthe machine) by a suitable escape- 'menti mechanism. Actuator racks 36, each having a'. stop lugx 38 formed at itsforward end, are mounted for longitudinal sliding movement in slottedcomb members 40 and 4l, being guided also by cross rods 42, 44 and 46, the latter projecting through a longitudinal slot 48 formed in each of the. actuators. Long tension coil springs 43 are provided to movethe actuators 36 rearwardly.

`ljach ofi the actuators is provided with a rack 50 normally meshing with a toothed segment 52 pivoted upon a segment shaft 54. Also mounted upon the shaft 54 is a segment 56 complementary tothe segment 52, but which is capable of movement relative thereto through an angle corresponding to the pitch of the teeth on these segments to effect a transfer or carryover. For the latter purpose, the carrying pawl 58 is swung counter-clockwise sufficiently to permit the sidewardly extending lug formed upon the segment 5B to clear the end of the hook 62 formed at the upper end` ofthe-carrying pawl 58 and permit thefsegmentl 56 to move clockwise (Fig. 1) until ,theilug zis arrested by the contact with the bight portion 64 of the carrying pawl. The segment 56 is influenced to effect such carrying movement by a tension coil spring 66 which connects the segments 52 and 56 and is adapted to rotate the segment 56 counterclockwise with respect to the segment 52 until such relative movement is arrested by contact of the end surface 68 of the segment 56 with a sidewardly bent lug 10 formed on the segment 52. An aligner 51 is operated by suitable means to hold the segments 56 during the portions of the cycle when they are c stationary.

A set of accumulator wheels 12 mounted on an accumulator shaft 14 are adapted to be brought into mesh with the segments 56 and are respectively in mesh with subtracting pinions 16 mounted upon lsubtracting pinion shafts 18. The shafts 14 and 18 are carried by a movable frame consisting of two similar arms 80 which are suitably mounted for longitudinal sliding movement upon a tiltable frame 82. The frame 82 is oscillated upon each operation of the machine to bring the accumulator pinions 12 (or the subtracting pinions 16) into engagement with their respective actuating segments 56. The mechanism for accomplishing such engagement and disengagement of the accumulator pinions with the actuator may be of any suitable well-known construction, for example an adaptation of the wipe pawl mechanism shown in my aforesaid patent. When the accumulator pinions 12 are not in mesh with the segments 56, the frame in which they are mounted may be raised (from the position in which it is shown in Fig. 1) by means of a control bell crank 84, to bring the subtracting pinions 16 into position such that they will mesh with the segments 56 when the frame 82 is oscillated toward the segments 56. y

A platen 86 is suitably mounted upon the machine, preferably in a manner so that it may be readily detached to permit the removal of the casing I6, the platen being provided with the usual friction roller or rollers 88 and a serrated tear strip 90. Any suitable means for carrying a paper roll may be provided, the papervstrip 93 being fed in the usual marmer between the platen and the friction roller 88 and beneath the tear strip 90. A ribbon 92 is fed transversely across the machine in front of the platen 86 by a suitable ribbon feeding mechanism, one form Yof which will be hereinafter described.

The type, bearing the characters to 9 inclusive, are formed upon the periphery of a type wheel 94, each of which is suitably mounted for rotation upon a stud 96 secured to its associated type wheel carrying arm 08. Each of the type wheels 94 has a pinion |00 formed integrally therewith, or rigidly secured thereto. The pinions I 00 mesh with idler pinions 02 mounted upon studs |04 which, like the stud 96, are supported by their respective type wheel carrying arms 98. The idler pinions |02 are normally in mesh with their respective toothed segments 52.

The type wheel carrying arms S8 are mounted for pivotal movement upon a transverse rod |06 which is suitably supported in the side frame plates I2 and I4, and each of the arms has a forwardly extending ear |08 to which a tension coil spring I|0 is secured, the other ends of the coil springs |I0 being anchored to the transverse comb member 4| which also serves as a guide for the rearward ends of the actuator racks 36. The type wheel carrying arms 98 are restrained from clockwise pivotal movement under the influence of their respective tensioned coil springs I0 by a rod ||4 carried by bail arms I I6, the latter being pivoted upon the shaft |06. The type wheel carrying arms 98 are, as best shown in Figs. 1 and 6, guided in slots I|8 formed in a comb |20 which is secured between the frame plates l2 and I4. The comb |20 is also provided with slots |22 properly to space the segments 52. Further, the comb |20 is provided with guide surfaces |24 formed by widening the open end portions of the slots ||8, for engagement with the aligner arms |26. The aligners |26 are pivoted upon the shaft |06, and each has a tooth |28 adapted to engage between the teeth of the pinions |02 respectively when the latter are moved from meshing engagement with the teeth of the segments 52. The engagement of the aligner teeth |28 with their respective pinions takes place prior to the complete disengagement of the pinions from the selectors so that the pinions |02 (and hence the type wheels 94) are at all times either under the positive control of the segments 52, or are nonrotatably locked by the teeth |28 of the aligner pawls |26. Each of the aligner pawls |26 has a rearwardly extending ear I 30 forming an anchorage for a tension coil spring |32, the other end of which is connected to the adjacent type wheel carrying arm 98.

Each of the type wheel carrying arms 98 has, at its upper extremity, a saw-tooth projection |34 normally in engagement with the rearward edge of a slot |36 formed in a sear plate |38 which latter is secured to a shaft |40 pivotally mounted in the side frame plates I2 and I4. An actuating arm |42 is secured to the left hand end of the shaft |40 and has its free end pivotally connected to a link |44, the lower end of which is pivoted to the forwardly projecting arm |46 which is preferably integral with the arm ||6 (Figs. 1 and 2). The forward end of the arm |46 carries a roller |48 which is cooperable with the edge of a plate'cam |50. The cam |56 is secured to the main operating shaft |52 and is so shaped that the forward end of the lever |46, ||6 will be raised (the lever swung clockwise) just prior to the end` of the lforward stroke of the operating handle, and will be lowered (swung counterclockwise) at the beginning of the return stroke of the operating handle. r

Means are provided to prevent the rearward swinging movement of type wheel carrying arms 98 which are in denominational orders higher than that of the highest significant figure in the amount to be printed. In other words, although the machine illustrated is provided with ten number type wheels and carrying arms, when an amount having less than ten digits is to be imprinted, it is desirable to restrain the 'type wheel carriers for the unused higher denominational orders to prevent the printing of zeros to the left of the highest significant figure of the number being printed. This means comprises a plurality of restraining latches |54 pivotally mounted upon a cross shaft |56. Each of the latches |54 has a relatively long rearwardly extending arm |58 (Figs. l, 3, and 5) terminating in a sidewardly bent lug |60, an upwardly extending ear |62 having a sidewardly extending lug |64 anda downwardly projecting' arm |66 provided with a stop shoulder |68 and a diagonally bent tail portion |10. Each of the tail portions |10 has a tension spring |12 secured thereto, the other end of the spring being anchored to a bail bar |14 which is secured to, or formed integrally with, a pair of bail levers |16 pivoted upon the rod |56 and having their rearwardly projectingfarms connectedby links |-'|8 with Athe rod H4. The springs |12 normally `hold the stops shoulders |68 of` theslatchesi in engagement with the lower` edgel of the bail bar |14. The arms Hi8-and IKS-of the latches |54'are respectively guided in slots formed in a; guide comb |80 which is secured to `the side frame plates i2, I4. lThe sidewardly bent lugs |64 of the latches |54 lie beneath the Ypath ofomovement of the lower edges of their respective actuators 36,. so that if such a'ctuator is moved beyond its zero position, the lug |64 will abut against thelower edge of the actuator and the latch. thus held in substantially the position in which it is shown in Fig. l. If, however, the actuator 36 is not moved beyond its Zeroposition, its associated latch |534 will be free to swing clockwise when the bail bar |74 is swung clockwise just prior to the end of the forward stroke'of the operating handie. When a latch is thusswung clockwise (under the influence of its tension spring |12), the sidewardly extending lug |65 at the rear end of the arm |58 of the latch will drop behind a projection |32 formed en its associated type wheel carrying arm and thus prevent clockwise swinging movement of the; latter to its printing position when the type carrying arms are released by the raising of the sear |38. Further-- more, as best illustrated in Fig. 5, the tail portions I'm of each of the latches E54 overlie the adjacent edge |84 of the next adjacent higher denominational order latch, with the result that any latch in the tens or any higher denominational order which is held from clockwise movement (by virtue of the engagement of the lug |64- with Y the lower edge of the actuator rack 35) will be eiective similarly to hold all of the latches of lower denominational order in their normal positions substantially asshown in Fig. l, so that their associated type wheel carrying arms 93 will not be restrained from swinging movement by the lugs |60,

The edge of the slot 3 formed in the sear plate |38 is preferably so conformed, or the sear plate so shaped, that when the plate is raised the f type wheel carrying arms S8 will not be released simultaneously, but will be released successively or seriatim and will be swung by their respective springs |32 to cause their selectively positioned type forcibly to strike the ribbon 92 and l make a printing impression upon the paper strip Q3. With a printing mechanism of this character, the use of the usual' hammers for striking the type to cause the printing impression upon the paper is obviated and thus one of'the principal causes of noise in the'operation of adding machines eliminated. The` arrangement of the sear |38 by virtue of which the type wheel carrying arms are successively released' further reduces the amount of noise Yproduced during the operation of the machine. It will be noted that at the time that the sear |38 is raised to release the type wheel carryingarms, the bail rod 4 will have swung clockwise through an angle of about fifteen degrees so that the bail rod will not interfere with the clockwise swinging movement of the. type wheel carrying arms. However, after the printing has been effected, and during the initial portion of return stroke oi the operating handle, the levers consisting of arms |46 and It will be swung counterclockwise by means of the cam l 5S, and the bail rod I I4 thus brought into engage .lent with the heel portions |88 of the type wheel carrying arms 98 and swing such of the latter as have been: releasedback. to their normal positions (as showninFig. l)` with their saw-tooth projections |34 in latching engagement with the Sear plate |38.

In addition to the quietlyy operating printing' mechanism, I have provided a substantially silent full stroke mechanism to replace the usual noisy pawl and ratchet type of full stroke mechanism generally. used on adding machines and thus fur-- ther reduce the noise. This mechanism is best shown in Fig. '7, wherein the operating handle is freely pivoted upon the main operating shaft |52 and has an arm |96 rigidly secured thereto, by means of a screw |94, or other suitable means. This arm |96 is engageable'with a roller |98 suitably mounted upon a full stroke plate 239 which may pivot freely upon the main operating shaft |52. A relatively` powerful torsion coil spring 202. has one end anchored vby a suitable stud 204 to the full stroke plate-200, the coil of thespring `being wound about the shaft |52 and its other end anchored to a triangularly shaped plate 226 by means of a stud 208. Av full stroke clutch roller 2|!! is mounted for rotation at the end of the arm 2|2, the latter having a pin and roller 254 capable of slidu ing in a slot. 2|6 formed in the full stroke plate 20S. A compression coil spring 2:20 is `provided to push the pin andy roller 2|4"r outwardly in its slot 2|6 (away from the axis of the main operating shaft |52). The full stroke roller 72H3 is adapted to roll upon the inner edge of an arcuate rail 222 which is secured by means of studs 224 to a secondary frame plate positioned to the right of the right side frame plate I2, and omitted from the drawings for the sake of clarity.

Pivotally mounted. upon thelrail 222 is a bell crank latch 226, the forwardly extending arm of which is normally held downwardly by a tension coil spring 228, such downward movement (counterclockwise, Fig. 7) being limited by a pin 230 which is engageable with the outer edge of the rail 222. The downwardly extending arm 232 of the bell crank latch 226 has la comming surface 234 formed on its rearward edge, and its lower end edge 236 is adapted to serve as a latch stop engageablewith a stud 240 secured in the full stroke plate 200, under circumstances .hereinafter to be described. A pair of pins 242 and 244 secured to the auxiliary frame plate at the right of the machine project into the path of movement of the arm 2| 2 which carries the full stroke roller 2| 0 and are adapted to be engaged thereby at the respective ends of the stroke of the latter so as to shift the roller 2 I ll to opposite sides of the slot 2|6. In other Words, upon the end of the return stroke, the arm 2|2 engages the pin 242 and swings the latter counterclockwise to the position in which it is shown in full lines in Fig, '7. At the end of the forward stroke of the operating handle, the arm 2|2 engages the pin 244 and the arm is thereby swung clockwise from its former position relative to the full stroke plate 20D to the position in which it is shown in dotted lines in Fig. 7. From this description, it will be apparent that during counterclockwise swinging or rotary movement of the full stroke plate 200 the roller 2|0 will roll freely along the inner edge of the rail 222 since any tendency for the roller to bind between the inner edge of the rail 222 and the upper edge 24B of the full stroke plate 200 will result in slight clockwise pivotal movement of the arm 2|2, but with the. roller rolling freelyy upon the rail, such movement of the arm 2|2 will not be sufficient to throwy thev arm past.` its dead center against the compressive force of the spring 220. If, however, after ycompletion of a portion only of the forward stroke of the operating handle, it is attempted to move the handle in the direction of its return stroke, the roller 2|0 will bind between the inner edge of the rail 222 and the upper edge 246 of the full stroke plate and lock the full stroke plate 200 against return movement in a manner similar to that employed in roller clutches. When the full stroke plate 200 reaches the forward limit of its stroke, the stud 240 will engage beneath the stop surface 236 of the bell crank latch 226 if, due to some irregularity in the operation of the adding machine,

the triangular plate 206 has not followed exactly f the movement of the full stroke plate. If, however, the adding machine mechanism is operating properly, and the operating handle has not been pulled too rapidly, a stud 248 projecting from the upper end of the triangular plate 206 will engage the cam surface 234 of the depending arm 232 of the bell crank latch 226 and swing the latter clockwise against the tension of its spring 228, thereby to shift the stop surface 236 thereof out of the path of the stud 240, and thus permitting the stud 240 and its full stroke plate 200 to commence its return stroke.

The main shaft |52 is operated upon its return stroke by means of a relatively strong tension coil spring 250 which is secured to a plate 252 by means of a chain 254, the plate 252 being pivotally secured to the main shaft |52. A driving connection between the tri-angular plate 206 and the plate 252 is effected by means of a stud 255 which projects sidewardly from the plate 206 forming an abutment for the edge of the plate 252. Any suitable form of dashpot may be provided to control the speed of operation of the machine. f f

As best shown in Fig. '1, the platen 86 is providedwith a pair of ratchet wheels 256, 258, the teeth of which face in opposite directions. A pawl 260 having a tooth 262 is provided for engagement with the ratchet wheel 258 while a pawl 264 having a tooth 266 cooperates with the ratchet wheel 256. The pawls 260 and 254 are pivotally secured to an arm 268 which is secured to the main shaft |52. Each of the pawls is provided with an ear 210 to each of which one end of a tension coil spring 212 is attached, the

other ends of thesesprings being anchored to a stud 214. The springs 212 normally hold the pawls in the positions shown in Figurer?, the pawl 264 being in engagement with a stud 216. Thus, upon counterclockwise movement of the operating shaft |52, the pawl 264 will engagethe ratchet wheel 256 and rotate the platen in a counterclockwise direction through 4an angle corresponding to the pitch of two teeth of `the ratchet wheel 256, whereupon the inclined cam ming surface 218 formed on the pawl 264 will engage the guide stud 210 and disengage the tooth 266 of the pawl 264 from the ratchet wheel 256. During this rearward and upward movement of the pawls 260 and 264, which continues during the forward stroke of the operating handle, the retracting pawl 260 will, of course, slide over the teeth of the ratchet wheel 258. Upon the commencement of the return stroke of the operating handle (clockwise movement of the main shaft |52), the tooth262 of the pawl 260 will engage the ratchet wheel 258 and rotate the platen 86 clockwise through an angle represented by three times the pitch of the teeth on the ratchet wheel 258, thus bringing the amount printed upon the esisti record strip above the edge 280 of the casing I6 so that it will be clearly visible. It will thus be seen that the amounts printed upon the record strip 93 will be spaced one beneath another with the usual close spacing and yet the last amount printed will be made visible above the edge 280 of the casing shortly after the completion of the printing operation. If the platen were not rotated backwardly prior to the printing operation, the printing line would be several spaces below the line of sight at which the amount printed would be visible.

To` secure inking of the type wheels, I provide a pair of ribbon spools 282, detachably secured at each of the inner sides of the outer frames (not shown) upon suitable rotatable stub shafts 284 carried by brackets 285. A notched wheel 286 is nonrotatably secured to the right hand shaft 284. An arm 288 is pivotally mounted upon the right hand stub shaft 284, the outer end of the arm 288 being connected by a link 290 with the rfull stroke plate 200. A double acting pawl 292 has its pivot stud 294 mounted for sliding movement in a slot 296 formed in the arm 288, the pawl 292 being normally held in resilient engagement with the notched wheel 286 by a spring 291. The left hand ribbon spool 282 is similarly mounted upon the left side frame plate I4 and is provided with an ordinary pawl end ratchet friction drive feed which is operable to rotate the left hand ribbon spool in one direction only. The right hand ribbon spool is, however, capable of being driven in either direction by the double acting pawl 292. Whenever the tension upon the ribbon becomes sufcient, due to the fact that the full length of the ribbon has been wound upon the right hand spool 282, the pawl 292 snaps over to a position such that its point will project toward the opposite side of the arm 288 from the position in which it is shown in Fig. '1. In this way the direction of the ribbon feed is automatically reversed whenever all of the ribbon has been wound upon one of the spools. From the above, it will be understood that the ribbon will alternately wind upon each of the spools first in a clockwise and then in a counterclockwise direction. The ribbon 92 is fed from the spool past suitable guide posts 300 and 302 so as to lie in proper position between the type wheels 94 and the platen 86. The casing is provided with suitable apertures to permit insertion and removal of the ribbon spools 282 whenever it is found necessary to replace the ribbon. Other usual means, such as the means for detachably holding the ribbon spools upon the shafts 284, as are common in the art may be employed.

The segments 52 and thus the actuating racks 36 are returned to normal position by means of a bail rod 304 carried by a pair of bail arms 306 mounted upon the shaft 54. The bail rod 304 projects through suitable arcuate slots 308 formed in the segments 52. The shaft 54 is rotated by means best shown in Fig. 7, wherein the end of the shaft 54 is provided with a mutilated pinion 3|0, the teeth of which are in engagement with the teeth of a gear sector SI2. The gear sector has a generally U-shaped notch 3 I 4 formed therein for engagement by a roller 3| 6 rotatably mounted on a stud 3|8 which in turn is secured to a cam plate 320 rigidly secured to the main operating shaft |52. The roller 3|6 through engagement with the edges of the notch 3|4 formed in the sector 3|2 causes the latter to have an oscillatory movement about its pivot stud 322 near the beginning and near the end of the operating cycle.

Shortly after the commencement of the forward stroke of the operating handle, the gear sector 3|2 is swung clockwise and the shaft 54 thus turned counterclockwise so as tol permit movement of the sectors 52 and actuator racks 35 under the inuence of the springs 45. rlhen shortly prior to the completion of the return stroke of the operating handle, the gear sector l2 will be swung counterclockwise, and hence the shaft 54 rotated clockwise thereby, through the bail 304, restoring the segments 52 and actuator racks 36 to normal position as shown in Fig. 1.

The machine of my invention is operated in the usual manner of a ten-key adding machine. Upon depression of the keys I8, the amount desired to be added and printed is set up in the pin carriage 24, 2B, whereupon the `operating handle is swung forwardly to permit the springs 55 to move the actuator racks 35 rearwardly until their respective stop lugs 38 abut against such of the pins 24 as may havev been set in depressed position. The type wheels 94 are geared to the actuator racks 36 through the segments 52 and idler pinions |92 so that the item set up by means of the keyboard will be likewise set up in the type wheels 94. Near the forward end of the operating stroke, the bail rod H4 will be swung clockwise, thereby conditioning such of the type wheel carrying arms 9B as are not restrained from movement by their associated lugs Hill of the latch members |54 will be released by the sear 38 and will swing rapidly to printing position under the influence of their respective springs llt. Due to the relatively great weight of the type wheels S4 andthe parts which swing therewith when the type are moved to printing position, a relatively sharp blow resultant in a goed printing impression will occur as the type wheels strike the ribbon. However, since the blow is against the relatively soft material of the ribbon, backed by the record strip and platen, there will be very little noise and the usual relatively loud noise of metallic hammer striking metallic type as is found in the prior art adding machines of this general character is thereby avoided.

After the item has been printed upon the.

record strip, the platen is advanced a suflicient distance to bring the printed item above the upper edge 230 of the casing I5 so that the amount imprinted will be visible to the operator. Thereafter the type wheel carrying arms 98 will be returned to normal position by means of the bail rod l I4 in which position they are latched by the sear l38. Thereafter, the idler pinions m2 will again be brought into mesh with the segments 52 which will not have moved from their set positions during the printing operation. To assure that there shall be no movement of the segments 52, 54, an aligner 5l' is moved into mesh with the sectors 55 just prior to the time that the idler pinions |32 are disengaged from the segments 52. Upon remeshing of the idler pinions N2 with the segments 52, either the ac cumulator pinions 82 (or in the case of subtraction, the subtractor pinions '16) are brought into mesh with the sectors 52. Thereafter, the shaft 54 is rotated clockwise to return the sectors 5'2 together with their actuating racks 35 to normal positions and the amount entered into the accumulator. During this operation, the type wheels 94 will likewise be brought to normal or zero position, and the transfer or carry-over mechanism will be operated as may be necessary.

While' I have described the machine as being hand operated, it will be apparent to those skilled in the art that a suitable electric motor drive might be substituted for the operating handle, and while I have shown and described a particular embodiment of the invention, many variations and modiiications may be made without departing from the basic principles thereof, and coming within the scope of the claims which follow.

I claim:

l. In an adding machine, the combination of pivoted arms, a numeral type wheel carrying pinion and an intermeshing idler pinion rotatably mounted upon each of said arms, said type wheels having type characters upon the peripheral faces thereof, a platen, means for selectively rotating said type wheels to position a predetermined type thereof for cooperation with said platen, springs for moving said arms and type wheels toward said platen, a sear for holding said arms and type wheels from movement under the iniiuence of said springs, means to move said sear to release said arms and type wheels for movement toward said platen under the influence oi said springs, normally ineffective latching means individual to each of said arms and means to move said latching meansy prior to releasing movement of said soar to positions to restrain their respective arms from movement toward said platen, said latcl'iing means` having parts cooperable with said type wheel rotating means to prevent movement of said latches to arm restraining position when their associated type wheel'rotating means have been operated.

2. In an adding machine, a casing, the ccmbination of a pivoted arm, a type wheel rotatably mounted upon said arm, said type wheel having type characters upon the peripheral face thereof, said type wheel and arm being located within said casing at all times, a platen, means for selectively rotating said type wheel to position a predetermined type character thereof for cooperation with said platen, a spring for moving said arm and `type wheel toward said platen, a sear for holding said arm and type wheel from movement under the influence of said spring, and means to move said sear to release said arm and type wheel for movement toward said platen under they influence of said spring.

3. In an addingl machine, the combination oi a plurality of pivoted arms, a type wheel mounted for rotation upon each of said arms, a spring on each ol said arms for moving said arm and type wheel from type adjusting position to printing position, a Sear common to all of said armsv for holding said arms against movement by their respective springs, means'cooperable with said type wheels when they are in type adjusting position selectively to set the wheels for making a predetermined impression, and individual means movable respectively with said arms to hold said type wheels in set position during their movement toward and away from printing position while they are not in cooperative engagement with said selectivo type wheel setting means.

4. In an adding machine, the combination of a( plurality of pivoted arms, one for each denominational order, a type wheel mounted for rotation upon each of said arms, a spring on each of said arms for moving said arm and type wheel from type adjusting position to printing position, a sear common to all of said arms for holding said arms against movement by their respective springs, means cooperable with said type Wheels respectively when they are in type adjusting position selectively to set the wheels for making a predetermined impression, means individual to and movable with said arms respectively to hold said type wheels in set position during the periods of their movement toward and away from printing position while they are not in cooperative engagement with said selective type wheel setting means, and means controlled by the type wheel setting means of the highest denominational order which has been actuated to condition the arms of said denominational order and the arms of al1 lower denominational orders for actuation by their respective springs,

5. In an adding machine having a housing, the

combination of a plurality of type carrying mem- I bers, a type wheel mounted for rotation on each of said members, said type wheels having numeral type on their peripheral faces and being located within said housing at all times, a platen, resilient means engageable with said type carrying members to swing the latter toward said platen, a plurality of diierentially movable elements for selectively rotating each of said type wheels, latches for respectively holding said type wheels in engagement with one of said differentially movable elements, a restraining latch for each of said type carrying members cooperable with one of its associated diierentially movable elements to hold its associated type carrying member from movement-toward said platen, a sear common to all of said type carrying members for holding them against movement toward said platen, and means to operate said sear to release such of said type carrying members for such movement as are not held by their restraining latches.

6. In an adding machine, the combination of a plurality of type carrying arms, an integral type wheel and idler pinion meshing therewith mounted for rotation on each of said arms, said type wheels having numeral type on their peripheral faces, a platen, resilient means engageable with said type carrying arms to swing the latter toward said platen, dilferentially movable members for differentially rotating said type wheels, a common sear for holding all said type carrying arms with their type wheels in engagement with said differentially movable means, a

restraining latch for each of said type arms cooperable with said differentially movable members to hold its associated type arm from movement toward said platen, additional means common to all of said type arms for holding them against movement toward `said platen and for restoring said type arms from positions adjacent said platen to positions for rotation by said differentially movable members, and means to operate said latch to release said type arms for movement.

7. In an adding and listing machine, the combination of key controlled actuator racks, segments meshing with said racks, type wheels normally geared to said segments, a platen, pivoted arms each carrying one of said type Wheels, resilient means acting upon said arms to move said type wheels against said platen to make a printing impression, a sear for holding said type arms against movement by their respective resilient means, latching means operable to restrain movement of said arms, each of said latching means being cooperable with one of said arms and being controlled by the actuator rack associated with its arm, means to operate said Sear lo. to release said arms after the type wheels have been moved to selected positions by. said racks, and means to restore said arms to normal position in latching engagement with said sear and with said type wheels geared to said segments.

8. In an adding machine, the combination of an actuator rack, a gear meshing with said rack, a type wheel rotatable by said gear, an arm normally holding said type wheel in position for operation by said gear, a sear engaging said arm to hold the type wheel in such position, a platen, means to swing said arm to bring the type wheel thereon into printing engagement with said platen, a restraining latch having means engageable with said arm to hold it against movement toward said platen, and means on said latch engageable with said actuator rack to prevent said latch from restraining said arm.

9. In an adding and listing machine, the combination of key controlled actuators, toothed segments operable by said actuators, type Wheels normally geared to said segments, a platen, a plurality of elements each carrying one of said type wheels, resilient means acting upon said type carrying elements to move said type wheels against said platen to make a printing impression, a sear for holding said type carrying elements against movement by their respective springs, latching means operable to restrain movement of said elements, each of said latching means being cooperable with one of said elements and being controlled by the actuator associated with its element, means to cause movement of said latching means to restraining positions unless their associated actuators or a higher denominational order actuator has been operated, means to operate said sear to release said elements after the type wheels have been moved to selected positions by said actuators, and means to restore said elements to normal position in latching engagement with said sear.

10. In an adding machine, the combination of an actuator, a type Wheel rotatable by said actuator, an arm normally holding said type wheel in position for operation by said actuator, a sear engaging said arm to hold it in such position, a platen, resilient means to swing said arm to bring the type wheel thereon into printing engagement with said platen, a restraining latch having means engageable with said arm to hold it against movement toward said platen, means on said latch engageable with said actuator to prevent said latch from restraining said arm, and means to return said arm from the position in which its type wheel is in printing engagement with said platen to the position in which said arm is latched by said sear.

THOMAS O. MEHAN. 

